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Pagliusi M, Bonet IJM, Lemes JBP, Oliveira ALL, Carvalho NS, Tambeli CH, Parada CA, Sartori CR. Social defeat stress-induced hyperalgesia is mediated by nav 1.8+ nociceptive fibers. Neurosci Lett 2020; 729:135006. [PMID: 32387758 DOI: 10.1016/j.neulet.2020.135006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 04/17/2020] [Accepted: 04/20/2020] [Indexed: 10/24/2022]
Abstract
Recently the voltage-gated sodium (Nav) channels began to be studied as possible targets for analgesic drugs. In addition, specific Nav 1.8 blockers are currently being used to treat some types of chronic pain pathologies such as neuropathies and fibromyalgia. Nav 1.8+ fibers convey nociceptive information to brain structures belonging to the limbic system, which is involved in the pathophysiology of major depressive disorders. From this, using a model of chronic social defeat stress (SDS) and intrathecal injections of Nav 1.8 antisense, this study investigated the possible involvement of Nav 1.8+ nociceptive fibers in SDS- induced hyperalgesia in C57/BL mice. Our results showed that SDS induced a depressive-like behavior of social avoidance and increased the sensitivity to mechanical (electronic von Frey test) and chemical (capsaicin test) nociceptive stimuli. We also showed that intrathecal injection of Nav 1.8 antisense reversed the SDS-induced hyperalgesia as demonstrated by both, mechanical and chemical nociceptive tests. We confirmed the antisense efficacy and specificity in a separate no-defeated cohort through real-time PCR, which showed a significant reduction of Nav 1.8 mRNA and no reduction of Nav 1.7 and Nav 1.9 in the L4, L5 and L6 dorsal root ganglia (DRG). The present study advances the understanding of SDS-induced hyperalgesia, which seems to be dependent on Nav 1.8+ nociceptive fibers.
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Affiliation(s)
- Marco Pagliusi
- Department of Structural and Functional Biology, State University of Campinas, Rua Monteiro Lobato, 255, Cidade Universitaria Zeferino Vaz, Box 6109, Campinas, SP 13083-865, Brazil
| | - Ivan José Magayewski Bonet
- Department of Oral and Maxillofacial Surgery,University of California San Francisco, 513 Parnassus Ave, Box 0440 S709, San Francisco, CA 94143, United States
| | - Júlia Borges Paes Lemes
- Department of Structural and Functional Biology, State University of Campinas, Rua Monteiro Lobato, 255, Cidade Universitaria Zeferino Vaz, Box 6109, Campinas, SP 13083-865, Brazil
| | - Anna Lethicia Lima Oliveira
- Department of Structural and Functional Biology, State University of Campinas, Rua Monteiro Lobato, 255, Cidade Universitaria Zeferino Vaz, Box 6109, Campinas, SP 13083-865, Brazil
| | - Nathalia Santos Carvalho
- Department of Structural and Functional Biology, State University of Campinas, Rua Monteiro Lobato, 255, Cidade Universitaria Zeferino Vaz, Box 6109, Campinas, SP 13083-865, Brazil
| | - Claudia Herrera Tambeli
- Department of Structural and Functional Biology, State University of Campinas, Rua Monteiro Lobato, 255, Cidade Universitaria Zeferino Vaz, Box 6109, Campinas, SP 13083-865, Brazil
| | - Carlos Amilcar Parada
- Department of Structural and Functional Biology, State University of Campinas, Rua Monteiro Lobato, 255, Cidade Universitaria Zeferino Vaz, Box 6109, Campinas, SP 13083-865, Brazil
| | - Cesar Renato Sartori
- Department of Structural and Functional Biology, State University of Campinas, Rua Monteiro Lobato, 255, Cidade Universitaria Zeferino Vaz, Box 6109, Campinas, SP 13083-865, Brazil.
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Abstract
Fibromyalgia appears to present in subgroups with regard to biological pain induction, with primarily inflammatory, neuropathic/neurodegenerative, sympathetic, oxidative, nitrosative, or muscular factors and/or central sensitization. Recent research has also discussed glial activation or interrupted dopaminergic neurotransmission, as well as increased skin mast cells and mitochondrial dysfunction. Therapy is difficult, and the treatment options used so far mostly just have the potential to address only one of these aspects. As ambroxol addresses all of them in a single substance and furthermore also reduces visceral hypersensitivity, in fibromyalgia existing as irritable bowel syndrome or chronic bladder pain, it should be systematically investigated for this purpose. Encouraged by first clinical observations of two working groups using topical or oral ambroxol for fibromyalgia treatments, the present paper outlines the scientific argument for this approach by looking at each of the aforementioned aspects of this complex disease and summarizes putative modes of action of ambroxol. Nevertheless, at this point the evidence basis for ambroxol is not strong enough for clinical recommendation.
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Affiliation(s)
- Kai-Uwe Kern
- Institute of Pain Medicine/Pain Practice, Wiesbaden, Germany
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Abstract
BACKGROUND Neuropathic pain is difficult to treat, and the available options are often inadequate. The expectorant ambroxol also acts as a strong local anaesthetic and blocks sodium channels about 40 times more potently than lidocaine. It preferentially inhibits the channel subtype Nav 1.8, which is expressed especially in nociceptive C-fibres. In view of the low toxicity of ambroxol, it seemed reasonable to try using it for the treatment of neuropathic pain that failed to respond to other standard options. MATERIAL AND METHODS The medical records of seven patients with severe neuropathic pain and pain reduction following topical ambroxol treatment are reported retrospectively. As standard therapies had not proved sufficient, a topical ambroxol 20% cream was repeatedly applied by the patients in the area of neuropathic pain. RESULTS The reasons for neuropathic pain were postherpetic neuralgia (2 ×), mononeuropathy multiplex, phantom pain, deafferentation pain, postoperative neuralgia and foot neuropathy of unknown origin. The individual mean pain intensity reported was between 4 and 6/10 (NRS), maximum pain at 6-10/10 (NRS). The pain reduction achieved individually following ambroxol cream was 2-8 points (NRS) within 5-30 min and lasted for 3-8 h. Pain attacks were reduced in all five patients presenting with this problem. Four patients with no improvement after lidocaine 5% and one patient with no response to capsaicin 8% nevertheless experienced a pain reduction with topical ambroxol. No patient reported any side effects or skin changes during a treatment that has since been continued for up to 4 years. CONCLUSION Ambroxol acts as a strong local anaesthetic and preferentially inhibits the nociceptively relevant sodium channel subtype Nav 1.8. For the first time, we report below on a relevant pain relief following topical ambroxol 20% cream in patients with neuropathic pain. In view of the positive side effect profile, the clinical benefit in patients with pain should be investigated further.
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Affiliation(s)
- K-U Kern
- Institut für Schmerzmedizin/Schmerzpraxis Wiesbaden, Sonnenberger Str. 68, 65193, Wiesbaden, Germany.
| | - T Weiser
- Boehringer Ingelheim Pharma GmbH & Co. KG, Ingelheim, Germany
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